The conventional approach to simultaneously receiving multiple channels in a receiver is to simply provide multiple receivers, with a separate receiver assigned for each channel. Each additional receiver carries a penalty in terms of cost, weight, power and space requirements for additional hardware.
An alternate approach is to digitize the full range of a particular band of frequencies, and use digital signal processing (DSP) after digitization to process channels in the band. This approach may reduce the penalties described above. However, the capability is beyond currently available analog-to-digital converter (ADC) technology. Therefore, multiple ADC's are required to digitize multiple channels in a band.
A method has been proposed for providing multiple simultaneous access to signals within a band that are widely separated in frequency using a single ADC. The separate signals are translated in frequency so that they form a single, generally continuous composite band thereby eliminating the wide frequency gap between the signals. However, the translation requires mixing and filtering the different signals and a local oscillator for each signal. Dividing at least one band into portions that are overlapped further reduces the bandwidths. Thus although one ADC may be used, the additional hardware required for each signal does not reduce the overall cost and complexity associated with multiple ADC's.